Transesterification of unsaturated esters is not new to the art. Kobayashi et al, in U.S. Pat. No. 4,916,255, disclose a method for producing transesterification products of methacrylate esters including methyl methacrylate. The reaction takes place in the presence of a lithium catalyst, and temperatures as high as 110.degree. C. to 125.degree. C. Methanol and methyl methacrylate are removed as an azeotrope. Falize et al (U.S. Pat. No. 3,836,576) disclose reaction temperatures in the range of 95.degree. C. to 100.degree. C., and additionally disclose the use of an aromatic polymerization inhibitor.
Gabillet, in U.S. Pat. No. 4,791,221, discloses a process for preparing transesterification products of methyl methacrylate. The reaction takes place in the presence of a lithium catalyst. Here..i the problematic solubility of lithium catalysts is offset by the use of crown ethers and/or cryptands. Reaction temperature are in the range of 100.degree. C. to 140.degree. C., and methanol is removed using a hexane azeotrope.
Murakami et al, in U.S. Pat. No. 4,074,062, disclose a transesterification catalyst consisting of barium, thallium, molybdenum, and/or oxides of these. The process also uses an azeotrope, but focuses on the use of alcohols rather than the alkoxylated diol of applicants' invention.